1. Field of the Invention
The embodiments of the present invention relate to a light scanning apparatus that causes a mirror supporting portion, which is supports a mirror and is supported by a torsion beam on both sides of an axis, to swing in directions around the axis by torsion of the torsion beam, a light scanning control apparatus for controlling the light scanning apparatus, and a light scanning unit including the light scanning apparatus and the light scanning control apparatus.
2. Description of the Related Art
In an example of a light scanning apparatus disclosed in, for example, Japanese Laid-open Patent Publication No. 2012-208352, a mirror portion for reflecting an incident light is rotated around a rotational axis using an actuator that is formed by providing an upper electrode on the upper surface of the piezoelectric element and by providing a lower electrode on the lower surface of the piezoelectric element. In this actuator, by applying a drive voltage to the upper electrode and the lower electrode, the mirror portion is swung in a vertical direction and a horizontal direction relative to a reflection surface.
Movement of this actuator is controlled based on a tilt of the mirror portion obtained as an output of a piezoelectric sensor that is provided to the actuator and detects a voltage generated in a piezoelectric element while the mirror portion is driven and swung.
For example, the piezoelectric sensor has a structure similar to an actuator using a piezoelectric element and outputs a voltage corresponding to displacement of the mirror. One of an upper electrode and a lower electrode of this piezoelectric sensor may be grounded, and the other one of the upper electrode and the lower electrode may be connected to an output terminal of the piezoelectric sensor.